1. Field of the Invention
The present invention relates to an online charging server, and more particularly but not exclusively to an online charging server for the provision of prepay functions for wireless cellular networks.
2. Description of the Related Art
A communication system is a facility that enables communication between two or more entities such as user terminal equipment and/or network entities and other nodes associated with a communication system. The communication may comprise, for example, communication of voice, electronic mail (email), text messages, data, multimedia and so on.
The communication may be provided by a fixed line and/or wireless communication interfaces. A feature of wireless communication systems is that they provide mobility for the users thereof. An example of communication systems providing wireless communication is a public land mobile network (PLMN). An example of the fixed line system is a public switched telephone network (PSTN).
A communication system typically operates in accordance with a given standard or specification which sets out what the various elements of a system are permitted to do and how that should be achieved. For example, the standard or specification may define if the user, or more precisely user equipment, is provided with a circuit switched server or a packet switched server or both. Communication protocols and/or parameters which should be used for the connection are also typically defined. For example, the manner how communication shall be implemented between the user equipment and the elements of the communication networks is typically based on a predefined communication protocol. In other words, a specific set of “rules” on which the communication can be based needs to be defined to enable the user equipment to communicate via the communication system.
The introduction of Third Generation (3G) communication systems will significantly increase the possibilities for accessing services on the Internet via mobile user equipment (UE) as well as other types of UE.
Various user equipment (UE) such as computers (fixed or portable), mobile telephones, personal data assistants or organizers and so on are known to the skilled person and can be used to access the Internet to obtain services. Mobile user equipment referred to as a mobile station (MS) can be defined as a means that is capable of communication via a wireless interface with another device such as a base station of a mobile telecommunication network or any other station.
The term “service” used above and hereinafter will be understood to broadly cover any service or goods which a user may desire, require or be provided with. The term also will be understood to cover the provision of complimentary services. In particular, but not exclusively, the term “service” will be understood to include Internet protocol multimedia IM services, conferencing, telephony, gaming, rich call, presence, e-commerce and messaging e.g. instant messaging. A “service” may comprise two or more parts. For example, a video telephone service comprises a voice part and a video part. Alternatively two or more services may be provided at the same time, for example a gaming service and a chat room service may be provided at the same time.
The 3G Partnership Project (3GPP) is defining a reference architecture for the Universal Mobile Telecommunication System (UMTS) core network which will provide the users of user equipment UE with access to these services. This UMTS core network is divided into three principal domains. These are the Circuit Switched domain, the Packet Switched domain and the Internet Protocol Multimedia (IM) domain.
The latter of these, the IM domain, makes sure that multimedia services are adequately managed. The IM domain supports the Session Initiation Protocol (SIP) as developed by the Internet Engineering Task Force (IETF).
One aspect of management relevant for both IMS and non IMS systems (i.e. services provided to subscribers via service nodes outside the core network, e.g. multimedia messaging and location estimation services), is that of charging users for supply of services. Charging can be divided into two modes of charging. The first is on-line charging which is where the user effectively pre-pays for a service and the second is off-line charging where a user is billed for a service after the session. Thus the first charging method is implemented by pay-as-you-go systems whereas the second method is implemented where the user is billed at regular intervals for calls which the user has made.
Currently for on line charging any network function wishing to charge a user is required to pass a Credit Control Request message to a network element known in the art as an Online Charging System (OCS). Attempts to standardise the OCS architecture has been defined in standards such at the third generation partnership project (3GPP) technical specification (TR) 32.815. Furthermore the applications and some interfaces operated by the OCS have furthermore been standardised by 3GPP TS 32.296.
The architecture of the OCS as currently implemented within these standards has problems for any operator attempting to operate a unified (i.e. online and off line) billing system. As defined by the above standards the OCS contains an account database which is operated on by an account balance management system. The account balance management system and account database within the OCS is effectively a partial duplication of information held by the operator for the off line accounting system.